Supercritical Phase Alkylation Reactions over Solid Acid Catalysts

4 Supercritical Phase Alkylation Reactions over Solid Acid Catalysts 

Due to the Clean Air Act, increasing attention is paid to the production of alkylates, which is a very clean burning fuel and has a high MON (motor octane number) with a low octane sensitivity and moderate vapor pressure. Commercially operated alkylate production uses a liquid acid catalyst such as H2SO4 or HE, resulting in problems associated with cost, apparatus and the environment [47]. New synthetic methods utilizing solid acid catalysts have been developed but no commercial process has emerged due to fast catalyst deactivation [48]. 

As outlined above, application of SCFs to heterogeneous catalysis is of great interest [49]. Selected supercritical fluids can extract high-molecular-weight hydrocarbons from catalyst micropores to avoid catalyst deactivation [50] or to reactivate spent catalyst [51]. This section describes the application of SCFs to alkylation reactions on solid acid catalysts [52,53]. 

Commercially available H-USY (Catalyst Chemical Ind., Si02/Al203 = 8.6) catalyst was mainly utilized with pellets of 20-40 mesh. Before reaction it was calcined in flowing air for 3 h at 450 C in situ [54]. A continuous 

The critical pressures and critical temperatures of the fluids used were propane, 96.8 °C and 42 bar 2-methyl-propane (isobutane), 135 °C and 36 bar 2-methyl-butane, 188 °C and 33 bar. With the exception of propane, the alkanes acted here as both reactant and SCF. 

---